import edu.princeton.cs.algs4.Stack;
import edu.princeton.cs.algs4.StdIn;
import edu.princeton.cs.algs4.StdOut;

public class Evaluate {
    public static void main(String[] args){
        Stack<String> ops = new Stack<String>();
        Stack<Double> vals = new Stack<Double>();
        while(!StdIn.isEmpty()){
            String s = StdIn.readString();
            if (s.equals("("));
            else if (s.equals("+")) ops.push(s);
            else if (s.equals("-")) ops.push(s);
            else if (s.equals("*")) ops.push(s);
            else if (s.equals("/")) ops.push(s);
            else if (s.equals("sqrt")) ops.push(s);
            else if (s.equals(")")) {
                String op =  ops.pop();
                double v = vals.pop();
                if (op.equals("+")) v=v+vals.pop();
                else if (op.equals("-")) v=v-vals.pop();
                else if (op.equals("*")) v=v*vals.pop();
                else if (op.equals("/")) v=v/vals.pop();
                else if (op.equals("sqrt")) v=Math.sqrt(v);
                vals.push(v);
            }
            else vals.push(Double.parseDouble(s));
        }
        StdOut.println("结果是"+vals.pop());
    }
}
